Unified Frequency-Domain Analysis of Switched-Series-RC Passive Mixers and Samplers

作者：Soer Michiel C M^*; Klumperink Eric A M; de Boer Pieter Tjerk; van Vliet Frank E; Nauta Bram

来源：IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS, 2010, 57(10): 2618-2631.

DOI：10.1109/TCSI.2010.2046968

• Frequency conversion
• linear periodically time variant (LPTV)
• low noise
• noise folding
• passive mixing
• voltage sampling

A wide variety of voltage mixers and samplers are implemented with similar circuits employing switches, resistors, and capacitors. Restrictions on duty cycle, bandwidth, or output frequency are commonly used to obtain an analytical expression for the response of these circuits. This paper derives unified expressions without these restrictions. To this end, the circuits are decomposed into a polyphase multipath combination of single-ended or differential switched-series-RC kernels. Linear periodically time-variant network theory is used to find the harmonic transfer functions of the kernels and the effect of polyphase multipath combining. From the resulting transfer functions, the conversion gain, output noise, and noise figure can be calculated for arbitrary duty cycle, bandwidth, and output frequency. Applied to a circuit, the equations provide a mathematical basis for a clear distinction between a "mixing" and a "sampling" operating region while also covering the design space "in between." Circuit simulations and a comparison with mixers published in literature are performed to support the analysis.

• 出版日期2010-10