Disclosed herein are embodiments of a programmable phase adjusting circuit, a programmable phase adjusting mixer circuit and design structures for these circuits. These circuits comprise a variable delay device connected between input and output nodes. The device includes multiple FETs with input diffusion regions that are connected to a voltage rail via switches so that they can be selectively biased, gates that are connected in series to the input node so that a periodic input signal can be propagated sequentially through each of the gates and output diffusion regions that are connected in parallel to the output node. A current source is connected between the output node and another voltage rail for biasing the output node when the variable delay device is off. The variable delay device enables a circuit in which small increments of selectable phase adjustments can be made to the periodic input signal as a function of propagation delay.