A mm-wave digital transmitter based on a 60 GHz all-digital phase-locked loop (ADPLL) with wideband frequency modulation (FM) for FMCW radar applications is proposed. The fractional-N ADPLL employs a high-resolution 60 GHz digitally-controlled oscillator (DCO) and is capable of multi-rate two-point FM. It achieves a measured rms jitter of 590.2 fs, while the loop settles within 3 μs. The measured reference spur is only -74 dBc, the fractional spurs are below -62 dBc, with no other significant spurs. A closed-loop DCO gain linearization scheme realizes a GHz-level triangular chirp across multiple DCO tuning banks with a measured frequency error (i.e., nonlinearity) in the FMCW ramp of only 117 kHz rms for a 62 GHz carrier with 1.22 GHz bandwidth. The synthesizer is transformer-coupled to a 3-stage neutralized power amplifier (PA) that delivers +5 dBm to a 50 Ω load. Implemented in 65 nm CMOS, the transmitter prototype (including PA) consumes 89 mW from a 1.2 V supply.

https://researchrepository.ucd.ie/bitstream/10197/8627/1/2014-05_jssc_w-wu_mm-wave_tx_adpll.pdf

A 56.4-to-63.4 GHz Multi-Rate All-Digital Fractional-N PLL for FMCW Radar Applications in 65 nm CMOS

In this paper, the locking range of the injection-locked ring oscillators is investigated. To improve the injection efficiency and the locking range for superharmonic frequency division, a multiple-injection technique is proposed. Using a 0.18-mum CMOS process, a wideband frequency divider based on a three-stage ring oscillator is implemented for demonstration. With a tunable free-running frequency, the fabricated circuit provides 2:1 and 4:1 frequency division with a single-ended input signal ranging from 13 to 25 and 30 to 45 GHz, respectively. Compared with the case of the single-ended injection, the locking range of the frequency divider almost doubles when multiple-input injection with optimum phases is utilized. The experimental results exhibit good agreement with the theoretical derivation and the circuit simulation.

Analysis and Design of Wideband Injection-Locked Ring Oscillators With Multiple-Input Injection

Injection-locked oscillators divide at very high frequencies and consume low power. They are not widely deployed in commercial products because they operate over small, often unpredictable, ranges of input frequencies. Ring oscillators as dividers are interesting because they are compact, and capable of a multi-phase output, including quadrature phases. Using a generalized Adler's equation for large injections, we analyze the operation of injection-locked ring oscillators and derive expressions for the input lock range. We discover that injection in the correct progressive phases greatly widens the lock range; all that is needed is the right delay cell circuit, and the injection input in one or two phases. As proof of concept, divide-by-two and six prototypes are built. The measured lock range spans DC to 1.5 the free-running frequency, the highest reported to date.

Multi-Phase Injection Widens Lock Range of Ring-Oscillator-Based Frequency Dividers

This paper presents the dual-injection-locking technique to enhance the locking range of resonator-based frequency dividers. By fully utilizing the voltage and current injection of the input signal, the divider locking range is extended significantly. The 0.8-mW dual-injection-locked frequency divider was developed in 90-nm digital CMOS technology. The total chip size is 0.77 mm times 0.5 mm. Without any varactor or inductor tuning, the input signal frequency coverage of the divider is from 35.7 to 54.9 GHz. Combined with the excellent locking range and sub-milliwatt power consumption, the figure-of-merit of this work surpasses those of the previous resonator-based dividers by more than one order.

A 0.8-mW 55-GHz Dual-Injection-Locked CMOS Frequency Divider

A low voltage and wide locking range injection-locked frequency divider using a standard 018-/spl mu/m complementary metal oxide semiconductor (CMOS) process is presented The wide locking range and the low-voltage operation are performed by adding an injection nMOS between the differential outputs of the divider that contains on-chip transformers which result in positive feedback loops to swing the output signals above the supply and below the ground potential This dual-swing capability maximizes the carrier power and achieves low-voltage performance The measurement results show that at the supply voltage of 075-V, the divider free-running frequency is 202 GHz, and at the incident power of 0 dBm the locking range is about 149 GHz (3688%), from the incident frequency 327 to 464GHz

A wide locking range and low Voltage CMOS direct injection-locked frequency divider

An injection-locked oscillator topology is presented, based on MOS switches directly coupled to the LC tank of well-known LC oscillators. The direct injection-locking scheme features wide locking ranges, a very low input capacitance, and highest frequency capability. The direct locking and the tradeoff between power consumption and tank quality factor is verified through three test circuits in 0.13-/spl mu/m standard CMOS, aiming at input frequency ranges of 50, 40, and 15 GHz. The 40- and 50-GHz dividers consume 3 mW with locking ranges of 80 MHz and 1.5 GHz. The 15-GHz divider consumes 23 mW and features a locking range of 2.8 GHz.

M. Tiebout

Papers

A CMOS direct injection-locked oscillator topology as high-frequency low-power frequency divider