System and method for combined I/Q generation and selective phase interpolation

A system for combined generation of In-phase (I) and Quadrature (Q) signal references injection locked to a periodic injection signal and adjustable phase interpolation of an output signal with reference thereto comprising:

• a ring oscillator portion generating an oscillator clock signal, said ring oscillator portion including a plurality of delay stages interconnected in cascade to collectively execute an odd number of signal state inversions within a closed loop, said delay stages being configured to establish at respective nodes defined therebetween corresponding delayed versions of the oscillator clock signal successively shifted in phase by a predetermined phase difference;
• and
• a signal injection portion coupled to said ring oscillator portion selectively applying the periodic injection signal to at least one of said nodes for locking said oscillator signal thereto in frequency, said signal injection portion selectively varying a current amplitude of the periodic injection signal;
• wherein said signal injection portion is selectively actuated in single and split injection modes;
• said signal injection portion in said single injection mode applying the periodic injection signal exclusively to a selected one of said nodes, said delayed oscillator signal version thereafter established at the selected node thereby forming said I reference;
• and,
• said signal injection portion in said split injection mode applying said periodic injection signal concurrently to first and second ones of said nodes, said periodic injection signal being applied to said first node at a first current amplitude and to said second node at a second current amplitude, said I reference being offset in phase between said delayed oscillator signal versions established at said first and second nodes in proportional relation to a ratio of said first and second current amplitudes.

A method for generating In-phase (I) and Quadrature (Q) signal references according to a periodic injection signal and selective phase interpolating an output signal with reference thereto comprising:

• establishing a ring oscillator portion to generate an oscillator signal, said ring oscillator portion including a plurality of delay stages interconnected in cascade to collectively execute an odd number of signal state inversions within a closed loop;
• generating at respective nodes defined respectively between consecutive delay stages correspondingly delayed versions of the oscillator signal successively shifted in phase by a predetermined phase difference;
• applying the periodic injection signal selectively to at least one of said nodes for locking said oscillator signal thereto in frequency, the periodic injection signal being selectively varied in current amplitude;
• wherein the periodic injection signal is selectively applied in single or split injection modes to selectively position said I reference of the periodic injection signal with respect to a selected one of said nodes;
• applying the periodic injection signal in said single injection mode exclusively to the selected one of said nodes, said delayed oscillator signal version established at the selected node thereby forming said I reference;
• and,
• applying the periodic injection signal in said split injection mode concurrently to selected first and second ones of said nodes, said periodic injection signal being applied to said first node at a first current amplitude and to said second node at a second current amplitude, said I reference being offset in phase between said delayed oscillator signal versions thereafter established at said first and second nodes in comparative relation to a ratio of said first and second current amplitudes.