Receivers for millimeter-wave (mm-wave) 5G, with the ability to detect a low-power desired signal, in the vicinity of large power blockers, require highly linear circuitry with a large power consumption. Suppressing the out-of-band blockers reduces this power consumption. N-path filters (NPFs) have recently been used to reject interferers in adjacent channels, by using a tunable center frequency. The state-of-the-art NPFs at mm-wave, however, only have a limited attenuation or use a large chip area. In this thesis, a fourth-order NPF is designed for 26-30 GHz. The implemented filter combines two frequency-shifted NPFs to create a flat in-band response and a steep roll-off, without the use of a large passive baseband filter. A rejection of 14 dB in the center of the first adjacent channel is obtained. This increases up to 24 dB at far-out-of-band frequencies. The noise figure of 10-12 dB is the lowest of the state-of-the-art, due to the added low-noise amplifier (LNA) in front of the filter. Despite this LNA, the designed filter achieves a comparable power consumption (40 mW) and smaller area (0.2-0.3 µm) than the state-of-the-art. The filter designed in this thesis is the first reported active N-path filter at mm-wave. The bandwidth is among the smallest reported, while the estimated area is lower than the state-of-the-art.

The goal of this Bachelor graduation project is to make an electrical stimulator that can be used to help people empty their urinary bladder. Patients that are unable to relax the urethral sphincter are most commonly treated by mechanically emptying the bladder or by sacral root stimulation where the roots are selectively cut.

The stimulator to be made must send a high-frequency signal that cancels the blocking of the urethral sphincter. This method should be able to empty the bladder without the use of mechanical devices or selectively cutting nerves.

The whole project is divided into three parts: Control and Interface, Arbitrary Waveform Generator and Safety Module. These parts have been performed by three different subgroups. In this report, the Arbitrary Waveform Generator is discussed. The other parts are explained in the respective reports [1, 2].

The requirements for this waveform are to generate a biphasic pulse with frequencies ranging from 1 to 15 kHz. The amplitude range of this pulse should be adjustable between 0 and 10 mA and the pulse width and interphase delay should be fully adjustable. In order to generate this signal, a power management system was necessary. In addition to the power management system, the LPC1343 microcontroller was chosen to control the system. One of its functions is to control a DAC by communication using the SPI protocol. The DAC can linearly control the output voltages between 0 and the offered reference voltage, in this case 3.3 V by sending 10 bits of data. Using a voltage to current converter, made by the Interface and Control subgroup, the output voltage is converted to a current between 0 and 10 mA [1]. Three additional signals from the microcontroller operate an H-bridge. This is a switching circuit that is able to direct the generated current through a load. Using a timer and four interrupt moments, the three signals are generated that can make a cathodic pulse, anodic pulse and can disconnect the current source.

The chosen DAC has a close to ideal behavior. Therefore, the conversion from the microcontroller to the voltage to current converter is very precise. The H-bridge works best at low frequencies. At 1 kHz, around 2% of a total pulse of 127.2 μs is needed to reach 63% of the cathodic or anodic amplitude. At high frequencies, the time increases. At 15 kHz, 24% of a total pulse of 8.4 μs is needed to reach the amplitude.