Radio Frequency Integrated Circuit Design - Webs

96 Radio Frequency Integrated Circuit Design
Table 5.1
Applications and Benefits of Inductors
Circuit Application Benefit
LNA Input match, Simultaneous power and noise matching,
degeneration improved linearity
Tuned load Biasing for best linearity, filtering, less
problems with parasitic capacitance
now part of resonant circuit.
Mixer Degeneration Increased linearity, reduced noise
Oscillator Resonator Sets oscillating frequency, high Q circuit
results in reduced power requirement, lower
phase noise
Power amplifier Matching, loads Maximize voltage swings, higher
efficiency due to swing (inductor losses
reduce the efficiency)
in Figure 5.1. The metals must be placed in an insulating layer of silicon dioxide
(SiO2) to prevent different layers of metal from shorting with each other. Most
processes have several layers of metal in their back end. These metal layers can
also be used to build capacitors, inductors, and even resistors.
The bottom metal is usually tungsten, which is highly resistive. However,
unlike aluminum, gold, or copper, this metal has the property that it will not
Figure 5.1 Cross section of a typical bipolar back-end process.