RF Receiver Front-End Employing IIP2-Enhanced 25% Duty-Cycle Quadrature Passive Mixer for Advanced Cellular Applications

Abstract

This paper proposes a second-order input-referred intercept point (IIP2)-enhanced 25% duty-cycle local oscillator (LO) quadrature passive mixer configuration with developing a wideband radio frequency (RF) receiver front-end, suitable for 4G and 5G new radio (NR) sub-6 GHz applications. By combining mixer switches operated by several combinations of quadrature-phase RF and LO signals, the inherent second-order nonlinear characteristics produced by the asymmetric factors of the mixer are greatly improved without any additional calibration process. This second-order linearity improvement is theoretically analyzed in terms of the 25% duty-cycle mixing operations, and is compared to the linearity characteristic observed in the conventional mixer design. To validate the IIP2 performance improvement, a wideband RF receiver front-end with the proposed mixer design is fabricated in a 65-nm CMOS technology. The implemented receiver front-end incorporates a wideband low noise amplifier with a polyphase filter, the proposed quadrature passive mixers, wideband transimpedance amplifiers, and 25% duty-cycle LO circuitry. The performance is characterized mainly in the long-term evolution and 5G NR frequency bands, which range from 1800 MHz to 2700 MHz. The demonstrated design achieves approximately 16 dB higher mean values of the out-of-band (OB) IIP2s compared to a conventional design approach without calibration. The design also attains conversion gains greater than 43 dB, double-sideband noise figures less than 4.4 dB, OB IIP3s greater than −1.52 dBm, and OB input P1dB greater than −23.1 dBm, for all measured frequency bands even in the presence of transmitter blockers. The proposed configuration, excluding the LO circuitry, consumes a bias current of 17.4 mA with a nominal supply of 1.2 V. The active area of the proposed implemented design is 0.6 mm 2 .

Calibration-Free Blocker Rejection Broadband CMOS Low Noise Amplifier for Advanced Cellular Applications

“…The low-noise pre-amplifier as the first stage of the LNA is principally applied to present broadband input matching and low-noise characteristics. In this pre-amplifier design, an inverter-type complementary common-source (CS) amplifier structure is utilized with input devices of M 1N and M 1P and a feedback resistor of R F [26]. This current-reuse topology boosts the gain and lowers the NF performance.…”

Analysis of Non-Idealities on CMOS Passive Mixers

“…The following expression relates the image rejection ratio with the input quadrature imbalance [10]: Under ideal conditions, both single and double quadrature architectures cancel the image signal. However, the presence of non-idealities, such as device mismatches or imbalanced I and Q signals, leads to an imperfect cancellation [6]. These effects can be modeled as an error in the phase and/or amplitude in one input quadrature, while the rest of the system, including the other input, remains under ideal conditions [3].…”

“…This work is contextualized in the development of a CMOS integrated transceiver for remote antenna unit (RAU) applications. In it, a one-hundred-megahertz IF signal from an optical link is converted to a five-gigahertz RF band for wireless communication and vice Parameters such as linearity [6] and noise [7], and even mixer impedances [8], have been analyzed in detail in the literature for mixers; nevertheless, an imperfect balance complicates significantly the analysis of this kind of system. Thus, previous studies [3] do not delve into the relationship between an imbalance and the IRR, providing qualitative explanations instead and restricting the analysis to certain non-idealities.…”

A Four-Phase Passive Mixer-First Receiver With a Low-Power Complementary Common-Gate TIA

“…Since most of these receiver front-ends are used in portable devices, reducing the power consumption is necessary to increase battery life. Typically, two types of power consumption are associated with a receiver [1]- [7]: dynamic and static. The dynamic power consumption is due to the clock buffers driving the mixer switches, while the static power consumption is due to the radio frequency (RF) low noise amplifier (LNA) [8]- [11] and the baseband (BB) trans-impedance amplifier (TIA).…”

“…In recent years, [12]- [39] have employed a passive mixer as the first block of the receiver instead of an LNA. Mixer-first receivers [12]- [39] offer many advantages over traditional LNA-first receiver architectures [1]- [3], [5], [6], making them suitable for nextgeneration software-defined radios (SDRs). Some of these advantages include frequency tunability, high linearity, and blocker resilience.…”