Andrew T. K. Tang

A 3 /spl mu/V-offset operational amplifier with 20 nV//spl radic/Hz input noise PSD at DC employing both chopping and autozeroing

A 3 /spl mu/V offset op-amp has been designed using both autozeroing and chopping to give 20 nV//spl radic/Hz input noise at DC with low energy at the chopping frequency. The design includes additional circuitry for reduced switching transients. Power consumption is 4 mW from a 5 V supply. Die area is 0.6/spl times/1.12 mm using a 0.6 /spl mu/m double-poly double-metal CMOS process.

Blowing Polysilicon Fuses: What Conditions are Best?

A study has been conducted to understand polysilicon fuse blow mechanisms and determine optimized blow conditions. The correlation of optical microscope images, cross section SEM (scanning electron microscope) images, and electrical waveforms of fuses blown at different voltages revealed two different blow mechanisms. Furthermore, SEM images of fuses blown using different pulse widths showed the physical changes of fuses during the fuse blow process

Bandpass spread spectrum clocking for reduced clock spurs in autozeroed amplifiers

Amplifiers utilizing autozeroing suffer from clock spurs at the sampling frequency. This paper describes a method of controlling the clock in order to reduce the amplitude of the spurs in the frequency domain, allowing a wider spurious-free dynamic range for signals with bandwidths approaching or exceeding the sampling frequency. Improvements of 20 dB were measured when using this technique.

Architectures for Low-Offset Monolithic Op-Amps

This chapter will discuss circuit architectures for low-offset (<1OμV) op-amps. The techniques used fall into two categories: autozeroing and chopping [1]. Although these two classes of techniques could be used for low-offset amplifiers in general, the architectures presented here have been designed to process continuous-time signals. The architectures have also been designed for use as op-amps. This means they need to be stable when used with different feedback networks, i.e. they need to be compensated. Since the feedback network is application specific and left to the customer, most op-amps are designed to be stable with the greatest amount of feedback: unity closed-loop gain.