Multibit bandpass delta-sigma modulators using N-path structures

Wide-temperature range CMOS capacitance to digital convertor for MEMS pressure sensors

“…2, two holding capacitors C h1 and C h2 are used to store and subtract the virtual-ground voltage (caused by low frequency noises, and finite gain and offset of the operational amplifier) during the y = 0 and y = 1 clock phases, respectively [27]. Using CDS technique, the effective value of the operational amplifier offset becomes V os /A, and the effective operational amplifier gain becomes nearly A 2 (V os is the Op-Amp offset and A is the operational amplifier open loop gain) [29,30]. The values of C h1 and C h2 do not significantly influence the accuracy of the operation, as they are only used to store and cancel the offset voltages.…”

Mixer sequence design for N-path filters

“…While different filter structures are appropriate for different process nodes and requirements, interest seems to be increasing in N-path filters based on current trends in CMOS integration and the availability of faster transistors [1], [2], [3], [4], [6], [7], [8], [11].…”

“…Short proof : From the lemma and corollary in section 4.1, we only need to test the sequences in (12) satisfy (9) and (11).…”

“…Band pass filters (BPFs) are used in many applications including radio frequency (RF) receiver (RX) paths and band pass delta sigma analog to digital converters [11]. A problem with typical BPF implementations is that they require inductors, and it's difficult to implement high quality (Q) inductors in complementary metal oxide semiconductor (CMOS) processes.…”

Wide-area adaptive active noise cancellation

“…However, the plane wave model is used to study the effect of a more complicated wavefront. Assuming that the channel consists of pure time delay, the expression for the mean-square pressure at a point S (after cancellation) is given by where (4) A = & cyz (r) is equal to one ( l / r ) if the i-th noise source is a plane wave (point) source, p is the number of unwanted noise sources, m is the number of cancellation speakers, n,(t) is a random process describing the temporal variations of the sound pressure from the i-th source, and u Z ( t ) is a random process describing the temporal variations of the sound pressure from the i-th cancellation speaker. The distance between the i-th noise source and the measurement point is given by r.i and the distance between i-th cancellation speaker and the measurement point is given by rei.…”