A C-MOS IC is used for the buffer-amplifier (IC14) toimprove functionable sensitivity; the inverter amplifier (IC4)is very responsive even with a low signal level input.Together, these ensure quick and stable signal detectioneven at low RF signal level input.(3) Resistance components detectorResistance components are picked up by L8, and detectedby D8, D9 and Q5. The detected resistance components areamplified at the inverter amplifier (IC4a), and then applied tothe antenna tuner CPU (IC5, pin 1).3-4-3 MOTOR CONTROL CIRCUIT(CTRL AND TUNER UNITS)The control circuit of the internal antenna tuner consists ofthe CPU, EEPROM*, tuning motors and tuning relays.*Electronically-Erasable Programmable Read Only Memory(1) CPU and EEPROM (CTRL unit)The antenna tuner CPU (IC5) controls the tuning motors viathe motor controller (Q211–Q218, D211–D217) and tuningrelays, and memorizes the best preset position in 100 kHzsteps. The memory contents are stored in the EEPROM(IC6) without a backup battery.(2) Tuning motors (CTRL and TUNER units)A motor controller (Q211–Q218, D211–D217) rotates thetuning motors (TUNER unit; MF1, MF2) to obtain a lowSWR.