Passive keyless entry device

A passive keyless entry device comprising:

• an in-vehicle transceiver;
• and
• a portable transceiver,
• wherein the in-vehicle transceiver transmits a low-frequency request signal to the portable transceiver,
• the portable transceiver transmits a high-frequency instruction signal for controlling and operating an in-vehicle controlled apparatus in response to the request signal,
• the in-vehicle transceiver receives the instruction signal so as to control and operate the in-vehicle controlled apparatus,
• the in-vehicle transceiver has:
• a clock signal generating circuit that outputs clock signals;
• a control signal generating circuit that outputs a binary control signal having positive and negative values;
• a modulation circuit that forms a pulse modulation signal by modulating the clock signals by the binary control signal having positive and negative values;
• and
• a transmission circuit that has a half-bridge circuit having a pair of FETs, the pulse modulation signal being inputted to a common gate of the pair of FETs, and a low-frequency antenna constituting an LC resonance circuit being connected to an output end of the half-bridge circuit,
• the clock signals include a first clock signal and a second clock signal,
• predetermined time after the control signal is changed from the negative value to the positive value is formed by the first clock signal having a predetermined cycle, and
• time until the control signal is changed from the positive value to the negative value, immediately after the predetermined time lapses, is formed by the second clock signal that is shifted by half wavelength with respect to the first clock signal.