Transmitter with a wave shape measurement stage

A transmitter of an RFID communication system to transmit an amplitude modulated transmitter data signal in resonance in an RF-Field over the air and to receive a modulated receiver data signal, the transmitter comprising:

• a transmitter stage configured to generate the amplitude modulated transmitter data signal with a particular frequency and waveform based on a carrier signal generated by a carrier signal stage;
• an antenna connected to the transmitter stage via a matching circuit to transmit the amplitude modulated transmitter data signal in resonance in the RF-Field over the air;
• a receiver stage connected via the matching circuit to the antenna to receive the modulated receiver data signal;
• and
• a wave shape measurement stage to measure a shape of the received modulated receiver data signal with equivalent time sampling, wherein the receiver stage comprises a mixer to mix the received modulated receiver data signal with the carrier signal of the carrier signal stage and wherein the wave shape measurement stage comprises a delay stage to delay the carrier signal used in the transmitter stage or the carrier signal used for the mixer in the receiver stage by a delay period (DP) provided by a control logic to the delay stage,
• wherein the amplitude modulated transmitter data signal comprises a waveform of a sinus and wherein the wave shape measurement stage comprises a DC compensation stage connected to the mixer to retrieve a DC signal part at a frequency of 0 Hz of an output signal of the mixer as amplitude of the received modulated receiver data signal for the particular delay period (DP) provided by the control logic to be sampled by an AD converter stage of the receiver stage,
• wherein the DC compensation stage retrieves the DC part of the output signal according to the following formula:
• DC
• ⁢
• part
• =
• A
• LO
• *
• A
• TRx
• 2
• ⁢
• cos
• ⁢
• (
• φ
• )
• A
• L
• ⁢
• O
• =
• constant
• ;
• φ
• =
• phaseshift
• ⁢
• or
• ⁢
• delay
• ;
• A
• T
• ⁢
• R
• ⁢
• x
• =
• Received
• ⁢
• Amplitude
• .