A Broadband Low Loss On-Chip Passive Balun with Stacked Serpentine Structure

Abstract

The invention discloses a broadband low-loss passive balun on chip having a laminated winding structure. The balun on chip is provided with three layers of metal conducting wires. The metal conducting wires in a first layer are secondary conducting wires, the metal conducting wires in a second layer are primary conducting wires and the metal conducting wires in a third layer are ground wires. U-shaped continuous bent winding structures are formed between the heads and tails of the conducting wires of each layer. The geometrical shapes of all U-shaped bends are completely consistent. The U-shaped bends are broken from midpoints between the heads and tails of the secondary conducting wires in the first layer to form left and right discontinuous U-shaped bend sections. Single-end signals of an unbalanced end are connected with the heads of the primary conducting wires. The tails of the primary conducting wires are connected to the ground wires. The heads and tails of the secondary conducting wires are all connected with the ground wires. Breakpoints of the conducting wires in the same sections with the heads of the secondary conducting wires are normal phase signal output ends, and the breakpoints of the conducting wires in the same sections with the tails of the secondary conducting wires are inverted signal output ends. The single-end signals of the unbalanced end are convertedinto differential signals of a balanced end for output under the coupling action of the primary and secondary conducting wires. The ground wires reduce the insertion loss of the balun and simultaneously expand a gain bandwidth and a matched bandwidth.

Description

technical field [0001] The invention relates to a broadband passive balun, in particular to a broadband low-loss on-chip passive balun with a laminated meandering structure, which is suitable for millimeter wave circuits. Background technique [0002] In wireless receiving and transmitting systems, it is usually necessary to use a balun to convert single-ended signals to differential signals. For example, convert the single-ended signal received by the antenna into a differential signal and connect it to a low noise amplifier, or convert the differential signal into a single-ended signal and connect it to the antenna for transmission. Balun is a circuit device that completes the conversion function of single-ended signal and differential signal. The difficulty in its design lies in how to ensure good amplitude balance, phase balance and low insertion loss. [0003] Traditional structure baluns are mainly Marchand structure baluns and spiral structure transformer baluns. Th...

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Problems solved by technology

The structure shown in Figure 2(a) is a spiral transformer balun, which has good amplitude balance and phase balance, but the eddy current effect of the substrate is large, resulting in relatively large insertion loss, usually S21<-5dB

Moreover, the geometric structure is relatively complex, and there are intersections between the coils. As shown in Figure 2(b), the crossing wires must be bridged by different layers of metal, which makes it difficult to ensure that the geometric structure is completely symmetrical, which further deteriorates the amplitude balance and phase balance, especially at high The effect of cross section bridging is more serious when frequency

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