there are many ways to build a sinewave generator however todate I have not seen a med-low cost high spec. minimal IC design that surely is now possible. The ICL038 etc. are large ICs with eccentric intercoupled freq./duty cycle adjustment & the NTE864 version costs $54 at Mouser, while high pin count expensive DDS chips exist that require programming. Many low pin count square wave generators do exist (e.g., the SOT23-5 LTC1799) and can be coupled with, e.g., 8th order elliptical low pass switched capacitor filters for a two chip solution. One interesting chip is the MSI MSLOSC SO-8 programmable DDS sinewave generator that also requires an external clock (where to purchase such a chip ?). Low pin count uC's with internal D/A's can also be programmed, with RC or active filtering added, and optional crystals.
What would be useful for many applications is a low cost low power low distortion one resistor programmable sinewave generator in an SC23-5 pin package with GND, VCC, R_freq and Out pins (similar in concept to the LTC1799). The fifth pin could be used for an optional gain setting resistor. An internal high precision capacitor completes the timing reference, and frequency accuracy could be, e.g., R_freq accuracy+0.1% (though even 1% would be useful). Instead of R-freq current programming could be used with graceful transition from one freq. to another for modulation etc.
A variation on this is an SPI programmable MEMs clock version for very high freq. accuracy.
I am looking for a very small outline package such as the SOT23-5 with as few external components as possible. However the XR2206 is indeed a good quality solution in a larger format.
Would a SOT23-6 work? I know the PIC10F20x comes in those and the 200 version costs about 28 cents in ones, since I recently bought a few. You'd have to program it. If memory serves, the internal oscillator is of the 1% variety. The footprint I'm using is 0.100" x 0.145, outside corner to outside corner of the copper pads. (I apologize, but I didn't get enough from your original post to know what you need
ICs are designed and sold when there is either existing demand, or a perceived demand can be shown.
Just because you want something doesn't mean there is real demand. You haven't really even explained your need, you just want a simple to use IC for reasons that haven't been explained.
There isn't a lot of need for a wide range audio sine wave generator. No consumer device uses them, and most of the time when you need an audio sine wave, a single frequency or a few specific frequencies are all that are needed. Then you usually need a low distortion sinewave, since a common use would be for distortion testing. The lowest distortion schemes come easiest with those bulky components you don't like. And realistically, by the time you have those LC or RC networks to make a good sinewave, the cost of the needed active component (and its size) add nothing to the project, so it's easier to switch between multiple oscillators than switch the circuitry from frequency to frequency.
Almost forty years ago, there was a conjunction where solid state electronics allowed for putting a function generator in a single IC, and yet where there was still a general demand for such a device. A function generator is a general purpose device, so it covers a wide range of frequency, and might have input for controlling it by voltage, and has multiple output waveforms. Some outputs won't be perfect, which is the nature of a general device. In this case, the sinewave output is done by "forming" the triangle waveform with a matrix of diodes and resistors. You get a sinewave, but it's not low distortion. The various waveforms change as the duty cycle of the square wave output changes because that's the nature of the design, you generate a triangle by charging and discharging a capacitor, and the offshoot of that is a square wave, but once you start tampering to change the triangle into a ramp or change the duty cycle of the "square wave" output, that mangles the other two outputs. But the circuitry is really easy, and that's why such ICs became available.
Obviously at the time, they could be used in function generators, eliminating much of the circuitry that had been needed previously. There was also, though I have no idea how much the demand was in numbers, audio synthesizers, where you wanted a voltage controlled oscillator and multiple output waveforms.
One way or another, there was enough demand for the device, and any further applications was icing on the cake. Back then, there wasn't that much choice for audio frequency voltage controlled oscillators, those function generator ICs like the 8038 and the 2206 that someone else mentioned came more or less concurrent with the start of the PLL synthesizer revolution. Those function generator ICs gave a lot of flexibility, unlike the VCOs designed for PLLs.
But decades later, there still isn't much demand for a wide range sinewave oscillator. Plus, other schemes have come along to fill the need for oscillators. Analog synthesizers have pretty much disappeared, digital techniques doing it a lot better. Anything above a certain level would have a CPU anyway, so one might as well use that to generate any needed waveforms.
If it was simple to generate a good sinewave, then there'd have been such a device long ago. But it's not, so they have to consider how much demand for it.
If there's little demand, then the cost goes up. It's too specialized to be on the level of a 555. Chances are good that any time you really need a audio frequency sinewave, the only loss of not having an IC is the amount of space it takes up.
Well yes. I did not state that demand was high only that I desired it and it would be useful for many applications. A low cost SOT23-5 design would minimize board space and passive requirements. Applications include IR/Ultrasonic sensing/communication carrier waves, high freq. power circuits, sine tone generation, etc. and the list is likely almost as long as the number of contributors. I also see other posts looking for a similar part, and there are many circuit designs available attempting with different degrees of success to provide minimal &/or low distortion sinewave generators.
If I need a single sinewave I will select a lower cost resistor configured SPT23-5 part over an XR2206 everytime. The same would apply for multiple sinewaves, or freq. &/or amplitude modulation designs.
Whether or not the part is currently economically viable I cannot be certain, however based upon its merits I suspect that at the right price it is. In the past I have found myself looking for something that did not exist, yet did appear on the market a short time later (SSDs are one example) and this can be a case of many people recognizing a need and the required technological state of development at the same time.
The prior development path that you outline is very interesting (and I agree that the requirements for triangle/square & sine wave generation are substantially different), however remarkable new designs keep appearing on the market, such as programmable micro crystal oscillators, digital pots, or a low cost 0.4uV offset 5MHz R2R
1.1mApower opamp in an SOIC8 format, as manufacturers push back the boundaries. It may well soon be time to rethink the sinewave generator and develope a med-high spec almost trivial to configure option(s) in a minimal package, perhaps using PLL, MEMs, state machine/uC internal control/stabilization, uPower techniques etc.
It might indeed work, and I am looking at PIC and Silicon Labs uCs. The six pins would limit an interface to an R/2R D/A, & no internal D/ A is included, so a filtered PWM approach would probably be best. The filtered PWM approach produces a non-monotonic result, however if the THD is acceptable this may well be the lowest outline design possible.
It might indeed work, and I am looking at PIC and Silicon Labs uCs. The six pins would limit an interface to an R/2R D/A, & no internal D/ A is included, so a filtered PWM approach would probably be best. The filtered PWM approach produces a non-monotonic result, however if the THD is acceptable this may well be the lowest outline design possible.
Well, with all due respect, yes. I did not state that demand was high only that I desired such a part and it would be useful for many applications. A low cost SOT23-5 design would minimize board space and passive requirements. Applications include IR/Ultrasonic sensing/ communication carrier waves, high freq. power circuits, sine tone generation, etc. and the list is likely almost as long as the number of contributors. I also see other posts looking for a similar part, and there are many circuit designs available attempting with different degrees of success to provide minimal &/or low distortion sinewave generators.
If I need a single sinewave I will select a lower cost one or two resistor configured SPT23-5 part over an XR2206 everytime. The same would apply for multiple sinewaves, or freq. &/or amplitude modulation designs.
Whether or not the part is currently economically viable I cannot be certain, however based upon its merits I suspect that at the right price it is. In the past I have found myself looking for something that did not exist, yet did appear on the market a short time later (SSDs are one example) and this can be a case of many people recognizing a need and the required technological state of development at the same time.
The prior development path that you outline is very interesting (and I agree that the requirements for triangle/square & sine wave generation are substantially different), however remarkable new designs keep appearing on the market, such as programmable micro crystal oscillators, digital pots, or a low cost 0.4uV offset 5MHz R2R
1.1mApower opamp in an SOIC8 format, as manufacturers push back the boundaries. It may well soon be time to rethink the sinewave generator and develope a med-high spec almost trivial to configure option(s) in a minimal package, perhaps using PLL, MEMs, state machine/uC internal control/stabilization, uPower techniques etc.
Well, with all due respect, yes. I did not state that demand was high only that I desired such a part and it would be useful for many applications. A low cost SOT23-5 design would minimize board space and passive requirements. Applications include IR/Ultrasonic sensing/ communication carrier waves, high freq. power circuits, sine tone generation, etc. and the list is likely almost as long as the number of contributors. I also see other posts looking for a similar part, and there are many circuit designs available attempting with different degrees of success to provide minimal &/or low distortion sinewave generators.
If I need a single sinewave I will select a lower cost one or two resistor configured SPT23-5 part over an XR2206 everytime. The same would apply for multiple sinewaves, or freq. &/or amplitude modulation designs.
Whether or not the part is currently economically viable I cannot be certain, however based upon its merits I suspect that at the right price it is. In the past I have found myself looking for something that did not exist, yet did appear on the market a short time later (SSDs are one example) and this can be a case of many people recognizing a need and the required technological state of development at the same time.
The prior development path that you outline is very interesting (and I agree that the requirements for triangle/square & sine wave generation are substantially different), however remarkable new designs keep appearing on the market, such as programmable micro crystal oscillators, digital pots, or a low cost 0.4uV offset 5MHz
1.1mApower opamp in an SOT23-5 format, as manufacturers push back the boundaries. It may well soon be time to rethink the sinewave generator and develope a med-high spec almost trivial to configure option(s) in a minimal package, perhaps using PLL, MEMs, state machine/uC internal control/stabilization, uPower techniques etc.
Well, with all due respect, yes. I did not state that demand was high only that I desired such a part and it would be useful for many applications. A low cost SOT23-5 design would minimize board space and passive requirements. Applications include IR/Ultrasonic sensing/ communication carrier waves, high freq. power circuits, sine tone generation, etc. and the list is likely almost as long as the number of contributors. I also see other posts looking for a similar part, and there are many circuit designs available attempting with different degrees of success to provide minimal &/or low distortion sinewave generators.
If I need a single sinewave I will select a lower cost one or two resistor configured SPT23-5 part over an XR2206 everytime. The same would apply for multiple sinewaves, or freq. &/or amplitude modulation designs.
Whether or not the part is currently economically viable I cannot be certain, however based upon its merits I suspect that at the right price it is. In the past I have found myself looking for something that did not exist, yet did appear on the market a short time later (SSDs are one example) and this can be a case of many people recognizing a need and the required technological state of development at the same time.
The prior development path that you outline is very interesting (and I agree that the requirements for triangle/square & sine wave generation are substantially different), however remarkable new designs keep appearing on the market, such as programmable micro crystal oscillators, digital pots, or a low cost 0.4uV offset 5MHz
1.1mApower opamp in an SOT23-5 format, as manufacturers push back the boundaries. It may well soon be time to rethink the sinewave generator and develop a med-high spec almost trivial to configure option(s) in a minimal package, perhaps using PLL, MEMs, state machine/uC internal control/stabilization, uPower techniques etc.
Here on the other side of the pond the PIC10F200 is 0.64 EUR = $0.80 each, and from the same company as Newark (Farnell). The XR2206 is also listed as no longer being stocked. However $0.80 is still good value for low quantity projects. Farnell also have another related company, CPC, with exceptional end of stock bargains, including R, C and Zener 5x & 10x packs for as little as 0.01 EUR, and mains transformers for as little as 0.40 EUR (I just bought a few, and two will go back to back to make an isolation transformer).
Another possible sine generator option is the Cypress PSoC (I had forgotten about these) and these are available at Farnell for about
2.00+ EUR.
By software delta-sigma do you mean a form of pulse delay modulation and how do you get three states to the RC, +, 0 & - in order to avoid a non-monotonic response ? Do you switch the port pin between +, high impedance & 0V and send this to a mid rail biased capacitor ?
It gets my vote. I seem to be always in need of just such a simple sine wave generator, the last time being last week when all I wanted was a 1kHz 1V sine wave as a test signal on a board. A few % distortion would have been fine. It's always amazed me that a simple SOT-23-5 or SO8 device like that has not been produced. If you build it, they will come...
How about the P89LPC micros? The LPC904 has a DAC and is SO-8, but hard to get? The LPC9102 also has a DAC in a TSSOP14 package for $1.65ea from Mouser.
For delta-sigma, a periodically-run software loop, every pass through, sets a port pin either high or low. The average (rc lowpass filtered) voltage of that pin makes the desired sinewave, with of course a Vcc/2 DC offset. D-S differs from PWM in that the pulse train is statistical, not rigidly deterministic, and there's no duty-cycle quantization as with PWM. This is the "one-bit DAC" that some CD players use.
I don't know how high a frequency a PIC could make... it depends on compute power.
I understand. The feedback loop of the Sigma-Delta-Sigma takes care of a-priori unknown waveforms and any variations in the following filter and load (assuming you sample after the filter). For a fixed sinewave and RC filter the output pulse sequence could be determined beforehand and no feedback loop required as long as the DC offset was set by one or more resistors. All other things being equal this should allow for a faster output rate.
The audio Delta-Sigma usually has a high order low-pass filter to remove ripple and some will pass through an RC filter. Since even with a six pin uC solution there will be 4 port pins available, it makes sense to consider a higher order Delta-Sigma approach using three (+/
0/-) or more output levels (4 pins allow for 7minus/0/7plus levels), using one current setting resistor per pin, that will reduce filtering requirements and ripple. The output current sequence is set beforehand based upon the desired RC output error and error slope.
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