Oversampling time-to-digital converter

An oversampling time-to-digital converter, comprising:

• an input pulse generation circuit configured to generate two pulse signals from two input signals such that a time difference between respective start edges of the two pulse signals is equal to a time difference between respective edges of the two input signals and respective end edges of the two pulse signals match each other;
• a reference pulse generation circuit configured to generate two pulse signals from a reference clock signal such that a time difference between respective start edges of the two pulse signals is equal to a cycle of the reference clock signal and respective end edges of the pulse signals match each other;
• a swap circuit configured to receive the two pulse signals output from the reference pulse generation circuit and to swap the received two pulse signals in accordance with a control signal to output the pulse signals;
• a first time-to-current conversion circuit configured to output two pulse currents in accordance with respective pulse widths of the two pulse signals output from the input pulse generation circuit;
• a second time-to-current conversion circuit configured to output two pulse currents in accordance with respective pulse widths of the two pulse signals output from the swap circuit;
• a current mirror circuit configured such that one of the two pulse currents output from the first time-to-current conversion circuit and one of the two pulse currents output from the second time-to-current conversion circuit are connected to an input terminal of the current mirror circuit and the other of the two pulse currents output from the first time-to-current conversion circuit and the other of the two pulse currents output from the second time-to-current conversion circuit are connected to an output terminal of the current mirror circuit;
• an integration circuit configured to integrate a differential current between the pulse current connected to the output terminal of the current mirror circuit and an output current of the current mirror circuit;
• and
• a comparison circuit configured to compare an output signal of the integration circuit to a threshold voltage,
• wherein
• an output signal of the comparison circuit is given as the control signal to the swap circuit.

A pulse current generation circuit to whose input terminal a pulse signal is input and from whose output terminal a pulse current is ouput, whose pulse width corresponds to that of the pulse signal, comprising:

• a current source;
• a first switch element connected to the current source and configured to output the pulse current in accordance with the pulse signal;
• and
• a dummy path connected to the current source and configured to cause, when the first switch element is nonconductive, a current of the current source to flow.