A miniaturized lowpass filter (LPF) with ultrasharp response, good figure of merit (FOM), and simple structure is proposed. The designed structure is fabricated and measured with a 2.9 GHz cutoff frequency. The proposed LPF consists of high impedance lines that are loaded by three similar resonators and two uniform suppressing cells. The filter size is only 0.08 × 0.23 λ g, which indicates small circuit size. The proposed design exhibits good features, such as an ultrasharp roll-off rate of about 1609 dB/GHz and a good FOM of 162,820. The insertion loss of the proposed LPF is less than 0.14 dB in the passband. With these excellent obtained specifications and flat group delay, this structure can be used in wireless antennae.

No abstract

In this paper, a new method to decrease the dimensions of the microstrip structures and reducing the overall size of the class F amplifiers is presented. First, by using the PHEMT transistor with a conventional harmonic control circuit (HCC), a low-voltage class F amplifier in the L band frequency at the operating frequency of 1.75 GHz is introduced, which named primitive class F power amplifier. Then, this amplifier is optimized by using capacitor loaded transmission lines (CLTLs). The measurement results of the amplifier show that by using the CLTL structure, the overall size has been reduced 85% (0.23 λg × 0.17 λg). The maximum power-added efficiency (PAE) of the power amplifier is about 77.5 % and the power gain which has been reached to 18.33 dB. The desirable features of this power amplifier, along with its very small size, make this power amplifier a good choice to use for the global system for mobile communications.