An adjustable mixer for surface acoustic wave( SAW)-less radio frequency( RF) front-end is presented in this paper. Through changing the bias voltage,the presented mixer with reconfigurable voltage conversion gain( VCG) is suitable for multi-mode multi-standard( MMMS) applications. An equivalent local oscillator( LO) frequency-tunable high-Q band-pass filter( BPF) at low noise amplifier( LNA) output is used to reject the out-of-band interference signals. Base-band( BB) capacitor of the mixer is variable to obtain 15 kinds of intermediate frequency( IF) bandwidth( BW). The proposed passive mixer with LNA is implemented in TSMC 0. 18μm RF CMOS process and operates from 0. 5 to 2. 5 GHz with measured maximum out-of-band rejection larger than 40 d B. The measured VCG of the front-end can be changed from 5 to 17 d B; the maximum input intercept point( IIP3) is0 d Bm and the minimum noise figure( NF) is 3. 7 d B. The chip occupies an area of 0. 44 mm^2 including pads.
In this paper,detailed models of 14-bit 100 MS/s pipelined analog-to-digital converter( ADC)are presented. In order to help design of ADC system,blocks for pipelined ADC and disturbance sources are carefully analyzed. Critical parameters,such as capacitor mismatch,clock jitter are proposed and simulated. The pipelined ADC system is divided into five parts,clock generator,sample and hold( S/H) circuit,multiplying digital-to-analog converters( MDAC),backend,and digital correction. These blocks introduce several interferences,which attenuate performance of pipelined ADC severely. Modeling and simulations of these disturbance sources are presented particularly. A new model of S/H is introduced. Results derived from simulations can supervise design and optimization of the ADC system.
A 37 GHz wide-band programmable divide-by-N frequency divider(FD) composed of a divide-by-2 divider(acting as the first stage) and a divider with a division ratio range of 273–330(acting as the second stage) has been designed and fabricated using standard 90 nm CMOS technology. The second stage divider consists of a high-speed divide-by-8/9 dual-modulus prescaler, a pulse counter, and a swallow counter. Both the first stage divider(with high speed) and the divide-by-8/9 prescaler employ dynamic current-mode logic(DCML) structure to improve the operating performance. The first stage divider can work from 2 to 40 GHz and the whole divider covers a wide frequency range from 25 to 37 GHz. The input sensitivity is as low as-20 d Bm at 32 GHz and the phase noise at 37 GHz is less than-130 d Bc/Hz at an offset of 1 MHz. The whole chip dissipates 17.88 m W at a supply voltage of 1.2 V and occupies an area of only 730 μm×475 μm.
This paper presents the design and analysis of a high speed broadband divide-by-2 frequency divider. The proposed divider is a dynamic source-coupled logic（DSCL） structure formed with two dynamic-loading master-slave D latches,which enables high frequency operation and low power consumption.This divider exhibits a wide locking range from 7-27 GHz and the minimum power consumption is only 1.22 mW from a 1.2 V supply.The input sensitivity is as low as -25.4 dBm across the operating frequency range.This chip occupies 685×430μm^2 area with two on-chip spiral inductors in 90 nm CMOS process.
A low power VCO with a wide tuning range and low phase noise has been designed and realized in a standard 90 nm CMOS technology. A newly proposed current-reuse cross-connected pair is utilized as a negative conductance generator to compensate the energy loss of the resonator. The supply current is reduced by half compared to that of the conventional LC-VCO. An improved inversion-mode MOSFET（IMOS） varactor is introduced to extend the capacitance tuning range from 32.8% to 66%. A detailed analysis of the proposed varactor is provided. The VCO achieves a tuning range of 27–32.5 GHz, exhibiting a frequency tuning range（FTR） of 18.4%and a phase noise of –101.38 dBc/Hz at 1 MHz offset from a 30 GHz carrier, and shows an excellent FOM of –185dBc/Hz. With the voltage supply of 1.5 V, the core circuit of VCO draws only 2.1 m A DC current.
A CMOS low-noise amplifier （LNA） operating at 31.7 GHz with a low input return loss （S11） and high linearity is proposed. The wideband input matching was achieved by employing a simple LC compounded network to generate more than one S11 dip below -10 dB level. The principle of the matching circuit is analyzed and the critical factors with significant effect on the input impedance （Zin） are determined. The relationship between the input impedance and the load configuration is explored in depth, which is seldom concentrated upon previously. In addition, the noise of the input stage is modeled using a cascading matrix instead of conventional noise theory. In this way Zin and the noise figure can be calculated using one uniform formula. The linearity analysis is also performed in this paper. Finally, an LNA was designed for demonstration purposes. The measurement results show that the proposed LNA achieves a maximum power gain of 9.7 dB and an input return loss of 〈 -10 dB from 29 GHz to an elevated frequency limited by the measuring range. The measured input-referred compression point and the third order inter-modulation point are -7.8 and 5.8 dBm, respectively. The LNA is fabricated in a 90-nm RF CMOS process and occupies an area of 755 × 670μm2 including pads. The whole circuit dissipates a DC power of 24 mW from one 1.3-V supply.
Two essential blocks for the PLLs based on CP, a phase-frequency detector （PFD） and an improved current steering charge-pump （CP）, are developed. The mechanisms for widening the phase error detection range and eliminating the dead zone are analyzed and applied in our design to optimize the proposed PFD. To obtain excellent current matching and minimum current variation over a wide output voltage range, an improved structure for the proposed CP is developed by fully utilizing many additional sub-circuits. Implemented in a standard 90-nm CMOS process, the proposed PFD achieves a phase error detection range from -354° to 354° and the improved CP demonstrates a current mismatch of less than 1.1% and a pump-current variation of 4% across the output voltage, swinging from 0.2 to 1.1 V, and the power consumption is 1.3 mW under a 1.2-V supply.
