Michael Andrews

Terahertz CMOS Frequency Generator Using Linear Superposition Technique

A low Terahertz (324 GHz) frequency generator is realized in 90 nm CMOS by linearly superimposing quadruple (N=4) phase shifted fundamental signals at one fourth of the output frequency (81 GHz). The developed technique minimizes the fundamental, second and third order harmonics without extra filtering and results in a high fundamental-to-4 th harmonic signal conversion ratio of 0.17 or -15.4 dB. The demonstrated prototype produces a calibrated -46 dBm output power when biased at 1 V and 12 mA with 4 GHz tuning range and extrapolated phase noise of -91 dBc/Hz at 10 MHz frequency offset. The linear superposition (LS) technique can be generalized for all even number cases (N=2k, where k=1,2,3,4,...,n) with different tradeoffs in output power and frequency. As CMOS continues to scale, we anticipate the LS N=4 VCO to generate signals beyond 2 Terahertz by using 22 nm CMOS and produce output power up to -1.5 dBm with 1.7% power added efficiency with an LS VCO + Class-B Power Amplifier cascaded circuit architecture.

A systolic SBNR adaptive signal processor

A new realization for adaptive signal processing units is proposed which uses a special subset of signed-digit number representations (SDNRs). This signed binary number representation (SBNR) captures all of the efficiencies of SDNR arithmetic and, in addition makes circuit realizations less complex. Furthermore, a natural interface between analog and digital numbers is provided. The serial online processing nature of SBNR utilizes the MSB first. An area/time complexity for VLSI implementations in comparable systolic array architectures contrasts the effectiveness of five different primitive VLSI cells and organizations.

A 220GHz wafer probe tip with reduced stray fields

A 220 GHz ground-signal-ground wafer probe is described with significantly reduced stray fields near the tip. The upper frequency limit in mm-wave wafer probes is constrained by the size of the probe tip area and stray fields. Measurements of the near-field tip area using a modulated scatterer instrument are presented. A new reduced dimension self-shielding tip design is shown with measured 140 GHz to 220 GHz S-parameter data. Measurements of 0 to 40 GHz crosstalk between pair of tips shows a 10 dB improvement over the present state-of-the-art.