Baker's Best

The non-negotiable single-supply operational amplifier
By Bonnie Baker, 5/28/2009
Analog devices that serve applications such as high-resolution delta-sigma or SAR (successive-approximation-register) converter systems are feeling the crunch from amplifiers that have difficulty with achieving good rail-to-rail input performance.

Where did all that racket come from?
By Bonnie Baker, 4/23/2009
To optimize a complementary-input-single-supply amplifier's THD+N (total-harmonic-distortion-plus-noise) performance, place the amplifier in an inverting-gain configuration and keep the closed-loop gain low.

Understanding FFT plots
By Bonnie Baker, 3/19/2009
The specifications of interest in an FFT (fast-Fourier-transform) plot are the fundamental input signal, the SNR (signal-to-noise ratio), the THD (total harmonic distortion), and the average noise floor.

Throw those bits away
By Bonnie Baker, 2/19/2009
You may find that a 12-bit converter system ends up costing you more money, real estate, and headaches than an alternative 24-bit system.

Match sensor to converter or converter to sensor
By Bonnie Baker, 1/22/2009
An alternative approach to designing an analog-to-digital converter system: Use a 24-bit converter to eliminate gain modules as well as the contributed offset, drift, and noise that you find in a 12- to 16-bit system.

What’s in your SAR-ADC application?
By Bonnie Baker, 12/15/2008
Driving a SAR ADC with an amplifier seems like a simple task. Not so fast. You are not finished until you accommodate the effects of the ADC-input charge injection on your amplifier.

Just use a 100Ω resistor: Understanding a rule of thumb for oscillating amplifiers
By Bonnie Baker, 11/27/2008
A capacitor and a resistor that hang on the output of an amplifier change the amplifier's open-loop-gain curve.

Transimpedance-amplifier application: The pulse oximeter
By Bonnie Baker, 10/30/2008
A demanding medical-electronics application, the pulse oximeter requires careful selection and implementation of a transimpedance amplifier.

Transimpedance-amplifier-noise issues
By Bonnie Baker, 10/2/2008
How much noise is too much noise in a photodiode-preamplifier circuit? Calculate the noise performance of a transimpedance amplifier by considering six regions in the frequency spectrum and adding each region with a root-sum-square equation.

Transimpedance-amplifier stability is key in light-sensing applications
By Bonnie Baker, 9/4/2008
A variety of precision applications sense light and convert that information into a useful digital word. Armed with a Bode plot, the designer must carefully correct circuit instability in the application's front end.

Photo-sensing circuits: The eyes of the electronic world are watching
By Bonnie Baker, 8/7/2008
Baker's Best: When exploiting the light sensitivity of silicon, the challenge lies in determining how to convert the low-level currents from the photo sensor into a useful electrical representation.

“Muxing” around with delta-sigma converters
By Bonnie Baker, 7/10/2008
The appropriate delta-sigma-converter class for multiplexed applications performs the conversion task with a zero-cycle-latency characteristic.

Analog filter eases delta-sigma-converter design
By Bonnie Baker, 6/12/2008
With this “easy-to-design” circuit, you can tackle the major noise contributors around the delta-sigma modulator’s sampling frequency.

RMS and peak-to-peak noise trade-off
By Bonnie Baker, 5/13/2008
If you are putting output data from an ADC into a digital display, the peak-to-peak noise representation becomes important.

ADCs: Does ENOB tell the whole story?
By Bonnie Baker, 4/17/2008
When evaluating an analog-to-digital converter, remember that the ENOB (effective number of bits) value describes only part of the ADC: noise and distortion. In some cases, the ENOB value may be misleading.

Delta-sigma ADCs in a nutshell, part 4: noise versus data rate
By Bonnie Baker, 3/20/2008
"Effective resolution" describes the useful bits from an analog-to-digital conversion as they relate to signal noise.

Delta-sigma ADCs in a nutshell, part 3: the digital/decimator filter
By Bonnie Baker, 2/21/2008
A digital-filter function attenuates the noise, and the decimator function slows the output data rate.

Delta-sigma ADCs in a nutshell, part 2: the modulator
By Bonnie Baker, 1/17/2008
Unlike most quantizers, the delta-sigma modulator includes an integrator that shapes the quantization noise.

Delta-sigma ADCs in a nutshell
By Bonnie Baker, 12/14/2007
Part one of a three-part series exploring the basic topology and functions of delta-sigma ADCs.

ADC voltage-reference errors impact full-scale conversions
By Bonnie Baker, 11/22/2007
SAR (successive-approximation-register) analog-to-digital references have more influence on conversion accuracy than you may initially think.

Voltage- and current-feedback amps are almost the same
By Bonnie Baker, 10/25/2007
The application-circuit configurations for voltage- and current-feedback amps are generally the same, except for a few key points.

Reach out and touch: Designing with touchscreens
By Bonnie Baker, 9/27/2007
Although the touchscreen interface may be digital, the human interface is purely analog.

Single-supply amplifier outputs don't swing rail to rail
By Bonnie Baker, 9/3/2007
Buyer beware: Linearity starts to degrade long before reaching the output-swing maximums.

How the SNRs of delta-sigma converters differ
By Bonnie Baker, 8/2/2007
This converter topology is a bit different from other topologies; however, many engineers still strive to fit this round peg of a converter into the standard ADC square hole.

Transimpedance strikes again: Current-to-voltage conversion with MDACs
By Bonnie Baker, 7/5/2007
A simple current-to-voltage conversion seems easy to implement with a DAC, amplifier, and resistor. However, this circuit presents stability issues.

SNR in ADCs: Where did all the bits go?
By Bonnie Baker, 6/7/2007
Theoretically, the SNR for any 16-bit converter should be 98.08 dB. But I see something different when I read converter data sheets.

Analog versus digital: Bridging the ADC-to-processor divide
By Bonnie Baker, 5/10/2007
Don’t take things for granted when you are designing the digital interface to a converter. Read the ADC data sheet and verify the bit positions in the transmission across the digital interface.

Wringing out thermistor nonlinearities
By Bonnie Baker, 4/12/2007
You can combine a series resistor, a microcontroller, a 10-bit ADC, and a programmable-gain amplifier to overcome the measurement difficulties of a nonlinear thermistor.

IBIS and Spice timing mismatches
By Bonnie Baker, 3/15/2007
Simulating an IBIS (I/O-buffer-information-specification) model alongside its transistor-level Spice counterpart creates a mismatch between the IBIS- and Spice-simulation waveforms.

Bonnie Baker, a senior applications engineer at Texas Instruments, gives an insider's view of analog design, both for the seasoned analog designer and for the digital engineer wading into unfamiliar territory.

Baker is the author of A Baker’s Dozen: Real Analog Solutions for Digital Designers. You can reach her at bonnie@ti.com.