External PLL Research Articles

A 120-GHz Electrical Interferometer for Contactless Permittivity Measurements With Direct Digital Read-Out

This work describes an electrical interferometer for contactless permittivity measurements working at 120 GHz. It was fabricated in a 130 nm SiGe process featuring an ft and fmax of 240 and 330 GHz. The on-chip system contains a 120 GHz VCO with a tuning range of 7 GHz featuring a divide-by-64 circuit to enable external PLL operation. The subsequent buffer provides 7 dBm of output power at 120 GHz. Additionally, the IC contains high-precision and high-resolution phase shifters based on a slow-wave transmission line approach with digital control for direct readout ability. A 120 GHz LNA with 17 dB gain and a power detector to provide DC output signals were realized on chip. It enables sample emulation capability by phase shift inducement in the measurement as well as a reference transmission line. In terms of phase detection, the system shows a sensitivity of 907.36 MHz/°.

A Broadband Double-Conversion RF Tuner

A prototype design of upconverter and downconverter units for a double-conversion cable-modem RF tuner are presented. The upconverter upconverts a channel from 47--862 MHz input band to around 1575 MHz intermediate frequency. The image-reject downconverter shifts the channel to 36.125 MHz (EU) or to 43.75 MHz (US). The upconverter includes a variable-gain low-noise amplifier, a double-balanced mixer, a three-stage VCO bank for LO generation and a divide-by-two circuit for driving an external PLL. The downconverter includes a LNA, image-reject mixers in Hartley configuration, a 3-stage polyphase filter, an IF-amplifier and a SAW driver. For the second LO generation the circuit includes a 6-GHz on-chip VCO, a divide-by-four circuit for quadrature LO and a divide-by-16 for feeding an external PLL. Signal reversal switching in the LO buffer can be used for the selection of LSB/USB injection. All building blocks are presented in this paper and experimental results are given from the upconverter, downconverter, and RF tuner demonstrator including SAW filters with center frequencies at 1575 and 44 MHz. The circuits are fabricated in a 0.9-? m SiGe bipolar process.