40GHz Wide-Locking-Range Regenerative Frequency Divider and Low-Phase-Noise Balanced VCO in 0.18μm CMOS

Abstract

Frequency dividers and VCOs are the most critical building blocks for the implementation of high-frequency signal sources that are widely used in wireline and wireless communication systems. In this paper, circuit topologies are presented to improve the performance of these high-frequency components. For the frequency divider, the proposed g m -enhancement technique incorporates the series and shunt inductive peaking in the resonator design. With the regenerative mechanism in the injection-locked frequency divider, a wide locking range can be achieved without using varactors for frequency tuning. As for the VCO, a balanced architecture is proposed for low phase noise while relaxing the stringent requirement on the start-up conditions at higher frequencies. Both of the circuits are designed and fabricated in a 0.18µm CMOS process.Injection-locked frequency dividers loaded with on-chip resonators are used to provide high-speed frequency division at low power consumption [1]. However, the limited locking range due to the high-Q resonators makes it difficult to cover the frequency tuning range of the VCOs under process and temperature variations. Tuning the free-running frequency with the varactors at the cost of a more complicated controlled mechanism when the divider is integrated in a system can extend the operating range of the divider. Alternatively, a regenerative divider with inductive loads presents an enhanced input bandwidth [2]. Due to the use of the mixer in the regenerative loop, higher power consumption is typically required. To overcome the design limitations, a g menhancement technique to increase the loop gain for regenerative frequency division is proposed. Figure 30.4.1 shows the block diagram of a regenerative divider that consists of a feedback loop with a mixer and a band-pass filter. As the input signal ω in mixes with the feedback signal ω in /2, frequency components of 3ω in /2 and ω in /2 are generated at the output of the mixer. With the selectivity of the LC-tank, frequency division is achieved provided that the open-loop gain for the component at ω in /2 exceeds unity. Consequently, it is desirable to maximize theloop-gain in the circuit design for wideband operations. A conventional circuit topology of the frequency divider is shown in Fig. 30.4.1, where the switching transistor M 1 acts as the mixer and the cross-coupled pair with the LC-tank forms the feedback loop [3]. As the RF signal applies at the gate, M 1 can be treated as a passive drainpumped mixer [4]. By biasing the gate voltage higher than the threshold voltage, the transconductance of M 1 is a nonlinear function of the drain voltage V ds . To maximize the effective transconductance g m,eff for an enhanced conversion gain, a series inductive peaking technique is adopted. By inserting the inductor L s in series with M 1 , the effective drain voltage V ds,eff increases as long as ω s >√[(ω LO 2 +ω d 2 )/2], where ω s =(L s C d ) -1 and ω d =(R ds C d ) -1 . Note that the maximum V ds,eff is obtained with ω s =√(ω LO 2 +ω d 2 )...

Excellent sensitivity 64.8‐GHz CMOS injection‐locked frequency divider with 10.2‐GHz locking range

“…As can be seen, the phase-noise of the ILFD was À128.97 dBc/Hz at 1 MHz offset when the input signal was locked at 54.6 GHz. A figure-of-merit (FOM) suitable for characterize the millimeter-wave frequency divider is defined as follows [10]:…”

Design of a 40 GHz CMOS Phase-Locked Loop Frequency Synthesizer Using Wide-Band Injection-Locked Frequency Divider

“…이러한 이유들로 인하여 그림 3(b)와 같 이 전압 제어 발진기와 ILFD 사이에 버퍼를 위치시키고, 전압 제어 발진기의 출력을 버퍼를 거쳐 ILFD 입력 단에 주입하는 방법이 선호된다 [6], [8], [10] 버퍼는 전압 제어 발진 기와 ILFD 상호간에 발생할 수 있는 간섭을 차단할 수 있 그림 2. 제안된 40-GHz PLL 구조 [12], [13] . ILFD의 입력 감도(input sensitivity) 시뮬레이션 결과이다.…”

A low-power CMOS injection-locked frequency divider based on hybrid differential injection technique

“…The dc power or the injected power level has to be increased for reaching a wide-locking-range characteristic in ILFD. In order to improve the locking-range issue, the ILFDs using an additional inductors to increase the injection efficiency have also been reported in [3][4][5]. In addition, the single injection is usually used in the conventional ILFD design through the tail injector or the direct injector.…”