Qiong Zou

Design of a Ku-band Low-Phase-Noise VCO Using the Dual

A Ku-band voltage-controlled oscillator (VCO) using dual tanks, together with feedback, is proposed and designed by using a 0.18-μm Bipolar compatible Complementary Metal Oxide Semiconductor (BiCMOS) process. A triple-coil transformer is employed to provide strong coupling between the two tanks and simultaneously introduce a transformer-based feedback. The parameters of the transformer are optimized to provide the required inductance ratios and reduce unwanted parasitic. The phase noise improvement for the proposed VCO is analyzed theoretically and verified by circuit and full-wave electromagnetic simulators. A benefit from the strong coupling between the two tanks, the proposed VCO achieves a low phase noise of -117.4 dBc/Hz at 1-MHz offset from an operation frequency of 12.64 GHz with a 4.3-mW power consumption of the VCO core.

LC

This work presents a millimeter-wave (mm-wave) dual-mode voltage-controlled oscillator (VCO) topology with switchable coupled VCO-cores for wide frequency tuning range and low phase noise application. By taking advantage of the different parasitic capacitance of cross-coupled pair when the VCO-core operates in ON and OFF states, the dual-mode operation of VCO can be realized, and the oscillations for both modes can be excited at the lower resonant frequency of tank, such that tank Q and phase noise performance could be improved for both modes. Strongly coupled transformer with large coupling coefficient (k) is utilized to increase the oscillation stability at the desired resonant frequency for both modes. The large k transformer will also facilitate the enhancement of tank Q at the lower resonant frequency. Frequency tuning range of the VCO is increased by properly designing the VCO-cores and combining the frequency bands of the two modes. In addition, the cross-coupled pair of VCO-core at OFF state is able to act as high Q active capacitor, which can further increase the tank Q and thus reduce the phase noise. Fabricated in a 0.18 μm BiCMOS process, the VCO exhibits a wide tuning range of 17.2% from 55.7 GHz to 66 GHz, and low phase noise from -87.5 dBc/Hz to -93.5 dBc/Hz at 1 MHz offset over the entire tuning range.

Tanks

Maintaining good power performance in a large bandwidth continues to challenge the design of millimeter-wave (mm-wave) power amplifiers (PAs), including mm-wave PAs with transformer-based matching networks (TMNs). With a TMN synthesizing method which is proposed based on the derived matching equations of TMN, this challenge is addressed in this paper for wideband mm-wave PAs by designing both inter-stage matching networks and output matching network with small mismatch in the entire operating bandwidth. A 60 GHz PA with synthesized TMNs is designed in a 65 nm bulk CMOS technology, achieving smaller degradation of power performance in the 9 GHz bandwidth compared to reported works in more advanced CMOS technologies. From 57 to 66 GHz, the PA is measured with saturated output power (PSAT) of 13.94 to 14.35 dBm, P1dBof 10.81 to 11.68 dBm, and peak power added efficiency (PAE) of 18.9% to 21.1%. The PA is capable of delivering 16QAM modulated signal with output power larger than 10.8 dBm and PAE higher than 10.1% in all the 4 channels of 802.11ad when EVM is 8.91%.

A Low Phase Noise and Wide Tuning Range Millimeter-Wave VCO Using Switchable Coupled VCO-Cores

This paper presents a new multi-conversion super heterodyne architecture for 60GHz broadband wireless application. The proposed design consists of a three-stage conversion with the help of a 24GHz VCO and a divider. The local oscillator frequency stands far away from RF and both IF signals reduce inter-modulate interference. The first and second mixers sharing the same 24GHz VCO relax the complexity and lowering power consumption of both VCO and PLL. Reusing of LO signal without frequency doublers or triplers for multiple conversions reduces power, area and improves efficiency. The topology is symmetrical about the transmitter and receiver sections. This unique feature reduces any circuit mismatches and provides a balance load for the VCO. The proposed design is simulated with ADS at the system level. The transceiver shows high sensitivity and indicates low power design on chip.

A 65 nm CMOS Power Amplifier With Peak PAE above 18.9% From 57 to 66 GHz Using Synthesized Transformer-Based Matching Network

Higher loss of commercial silicon substrate, which has the substrate resistivity of about 10Ω · Cm, is always a headache for the IC designer. We proposed a generalized multiple coupled tanks topology, which can reduce the substrate loss and enhance the circuit performance. The general concept, analysis and circuit examples are presented in this paper for the demonstration and verification.

A fully symmetrical 60GHz transceiver architecture for IEEE 802.15.3c application

A transformer based multiple coupled LC tanks model for on-chip VCO design is introduced. The merits of adoption multiple coupled LC tanks can be Q factor enhancement for the equivalent LC tank of VCO, low power consumption, better amplitude swing and broad tuning range can be obtained. As an illustration case two low power Ku band VCOs using dual LC-tanks with/without feedback designed using a 0.18 μm BiCMOS process for low phase noise or wide tuning range are demonstrated.

Generalized multiple coupled tanks for silicon based RF/mm-wave IC (Invited)

A 36 GHz low power voltage controlled oscillator (VCO) is proposed and designed in 0.18 μm SiGe BiCMOS process. The VCO core part adopts a triple coupled transformer to provide feedbacks and to decouple the base voltage from the collector of the bipolar transistors, such that the voltage swing and phase noise can be improved. Besides, a transformer-based buffer is used to reduce the total power consumption of the design and provide matching. From the simulation results, the proposed VCO achieves low phase noise from -95 to -102.2dBc/Hz at 1MHz offset from the oscillation frequency while consumes only 5.76 mW DC power for the whole chip.

Transformer based multiple coupled LC tanks for on-chip VCO design and applications

This paper presents a novel 24/36-GHz double conversion heterodyne architecture for IEEE 802.15.3c (60-GHz) applications. The selection of the first local oscillator frequency as 36-GHz gives rise to an intermediate frequency that yields significant cost advantage by reusing the 24-GHz architecture adopted by the automotive industry for both the receiver and transmitter second stage frequency translation. The topology is symmetrical about the transmitter and receiver sections thus taking care of mismatch issues at the circuit level implementation. The system level simulation shows high image rejection ratio and low requirement on image rejection low noise amplifier (LNA) and mixer design. The proposed architecture reduces the influence of harmonics and sub-harmonics during the mixer phase and exhibits less inter-modulation interference.

A low power millimetre-wave VCO in 0.18 µm SiGe BiCMOS technology

A wideband 60 GHz VCO with linear tuning range is proposed in this paper. The transformer-based differential tuning scheme is proposed for the fine frequency tuning, and the varactor pairs are used for the coarse frequency tuning. The VCO demonstrated 22.2 % tuning range from 56.43 to 69.79 GHz. By using the differentially tuned scheme, the proposed VCO has a linear tuning range, which can be used in wide band frequency synthesizer where a constant loop gain is desired.